Trains4Africa
Because all Boys (and some girls) love Trains

DIODE MATRIX MADE EASY

If your layout is more than a simple oval, you probably have several routes which trains can traverse.
 
I found it to be somewhat of a pain to refer to a “Route Chart” and set a gaggle of turnouts to the correct position whenever I wanted to change routes.
Since I use Tortoise turnout motors, the conventional twin-coil diode matrix found in many model railroad wiring and electronics books didn’t pertain. The basic scheme allows up to six preset routes using only one rotary switch; if you need more than six routes, the expansion scheme shown allows virtually limitless expansion. This circuit should work just fine with other stall-motor turnout actuators, such as Switchmaster and Micro-Mark’s Switch Tender.

If you want turnout position indicators on your control panel (and/or on trackside signals), just add bi-color/bi-polar LEDs to each turnout motor as shown on Tortoise #4; if you don’t want ’em, just wire #4 the same way that #1-#3 are wired.

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If you don’t want to buy a handful of “wall-wart” power supplies — or just want something a bit beefier — you might consider building the basic “dual-rail” (complementary) power supply shown below. +/-9 volts should do nicely unless you add LEDs (as shown) for your control panel; with the LEDs, I suggest you build the +/-12 volt version. Make sure you attach heat sinks to the regulators (abbreviated “HS” in the parts list), as they’ll run plenty warm.


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